Pressure regulating valve for hydraulic brakes



Dec. '14, 1943.

E. H. PIRON 2,336,887 PRESSURE REGULATING' VALVE FOR HYDRAULIC BRAKES .Filed Nov. 29, 1940 2 Sheets-Sheet 1 I M P 1N VENT 0R. 2777/7 3 /70 E; H PIFZONI 2,336,88

PRESSURE REGULATZNG VALVE FOR HYDRAULIC Flled Nov. '39, 1940 Patented Dec. 14, 1943 HYDRAULIC BRAKES Emil H. Piron, New York, N. Y., assignor to Transit Research Corporation, corporation of New York Application November 29, 1940, Serial No. 367,828

8 Claims. (oi. 131-153) This invention relates to pressure regulating valves and has for its primary object to provide New York, N. Y., a

7 obtained because the spring reactions remain a valve for regulating the pressure of the brake operating fluid in a fluid such as is used on street railway vehicles.

The practice in the street car industry is to use frictional braking systems in which the brake application is caused by the action of compressed air and the release by springs, and in some cases the order is reversed and the brake application is caused by pre-loaded springs, and the release by fluid pressure or electro magnetic means. The present invention is applicable toeither system and functions to regulate the fluid pressure in the brake applying means so as to provide any desired braking action.

The present valve assembly comprises a housing formed with a valve chamber having an inlet and an outlet, dual valve controlling the inlet and outlet respectively, means responsive to fluid pressure in the valve chamber for opening the outlet valve, and means for opening the inlet valve. Another object is to provide an arrangement of the type above mentioned wherein the pressure necessary to open the inlet valve is transmitted through the outlet valve in a manner tending to more firmly close the outlet valve.

Another object is to provide an arrangement of the type above mentioned whereinthe pressure necessary to open the inlet valve and maintain the outlet valve closed is derived from a spring, and wherein the pressure of the spring is opposed by electro-magnetic means capable of operation through a range from zero opposition to a stage where it completely nullifles the action of the spring. In other words, the spring constitutes a substantially constant pressure meanscapable of operating the inlet and outlet valves up to the highest pressure range contemplated and the electro-magnet constitutes meansi'or regulating the pressure of the spring to provide iorregulation or the fluid pressure from its highest pressure down to zero pressure.

Another object is to provide a valve assembly of the type above mentioned in which the valves pressure braking system and their actuating means vary but a slight amount during operation, in order that equilibrium conditions may be established with displacements amounting to but a few thousanctiis of an inch. Thus, the device operates on the principle of balancing forces, rather than as a result or movement from one position to another, and therefore accurate pressure regulation may be substantially constant during operation.

Other objects and advantages will become more fully apparent as reference is bad to the accompanying drawings wherein my invention is illustrated, and in which Fig. 1 is a diagram illustrating the present valve in connection with a brake system,

Fig. 2 is a side elevation of the valve,

Fig. 3 is a plan view of the valve, and

Fig. 4 is a vertical cross section of the valve.

In Fig. 1 there is illustrated a shaft l, which might be imagined as beingeither an axle shaft or motor shaft of a street railway truck. If the shaft I is considered to be the axle of the truck, 2v designates a rail wheel secured thereon, and if it is considered'as being a motor shaft, '2 represents a brake drum. 'Pivoted adjacent the wheel or drum 2 is a brake shoe 3 which is connected by a rod 4 to a piston 5 in a cylinder 6. A

switch I3 in the supply circuit of the motor I which operates the pump I0, when the pressure which may be predetermined.

The accumulator 8 is connected by'a pipe line 15 o the cylinder 6,

pressure in the cylinder 6 according to the will 1 or the operator.

The hydraulic pressure is capable or completely retracting the shoe and there- I chamber 2| having an inlet port): which, ac-

Fig. 1, is connected to pressure, or, as illuscOrding to the diagram of the source of liquid under trated, to the accumulator the valve chamber 2| is closed by a removable 8. The lower end of ,plug 23 and at the upper end her 2| is'a valve seat 24.

. to'the upper end of the tube voir 9..

iusted to regulate .nection between iulcrum as, the set screw.

of the valve cham- A spring 25 seated against the plug 23 normally holds a ballvalve 26 against the seat 24.

Coaxial with the valve chamber 2| is a second valve chamber 21 containing a ball valve 29'. The two chambers 2| and 21 are connected by a coaxial bore 39 in which aspacer 3| is slidably received. The spacer 3| is ofa cross sectional shape such that. it' does not prevent flow of liquid through the bore 30, and is of a lengthfsuch that it holds the ball-29 elevated above the bottom or the chamber '21. The housing 29 has a second assess? as here contemplated oil under pressure ranging from'120 to 180 lbs. is admitted through the port 22 into the valve chamber 2|. The valve 26 is, at this time, held against the seat 24 by the spring '25, and as oil under pressure is admitted to the chamber 2| it increases th total port 32, opening into the valve chamber 21 which, i

in the relationship shown in the diagram, is the port connected to the cylinder6. Anupper housing'section between the two housing upon which a Sylphon bellows 36 is mounted.

Secured to the free end of the bellows is a disc:

3'! in which a tube-38 is axially secured, as by welding. The ball valve 29 isfheld in seating contact with the lower end of the tube 38 by the spacer 3| when the-valve 26 is in contact with the seat 24.

38 is a nut in which a screw '40 isreceivedr The screw 46 has athreaded part 4|, a head 42 and an axial extension or pilot 43 which extends downwardly into the tube 38. A flexible diaphragm 44 is clamped at its outerlperiphery to the upper end of the-housing section 33 and at itscenter it is clamped between a spacer 45 and the nut 39 by tightening the nut" against the spacer.

Slidably mounted pllot43. The-tube 38 has radial ports 48 located in a plane above The housing section 33 which, in the arrange- Plvotally mounted on a fulcrum 50 is a balancingleveril. To one end of the lever 5| is connected a tension spring 52, the connection being established by nuts" 53 which'may be adplunger 54. of an 54 is established by a rod 56' having radial'pins .51 which engage two hookelike portions 58 on the lever. The pins 51 areheldagainstlateral move- .ment by a flange 59 disposed betweenthe two 'hooksfand the pins are constantly held. in' con- 52' acts topress mem ers 3 3 is secured; upon the housing'28 by means of bolts 34. Clamped' sections i a flange 35.

'Welded or otherwise secured in the tube 38 is a spacer I 46 of a cross sectional shape such that it does not obstruct. the flow of liquid throughthe tube.

The spacer 46'is pressed against the valve; 29 v by a spring 4'] sleeved onthe the tension; of the spring 52., The otherend of. the lever} is connectedto the electro-magnet 55. 1 The conthe lever 5| :and the plunger downwardly and by pressing its seat becomes present.

pressure holding the valve against its seat..

Accordingto one example, the orifice of the valve seat 24 is inch-and the pressure exerted by the spring is 112 lbs. With oil at a pressure of 120 to 180' lbs. its pressure amounts to 6 to 9 lbs. per square inch so that the total pressure holding the valve 26 against its seat will be 18 to 21 lbs.

sion in the bellows 36 and partly inthe diaphragm 44.- In a downward direction, it" is compensated for through the spacer 46, ball valve 29, spacer 3| and ball valve 26 by the upward reaction of the spring 25. As this last reaction is 12 lbs. the ball 26 against its seat when the oil pressure is zero, the pressure of ball 26, against 8 to 11 lbs. whenoil pressure is In other Words, 10 lbs. are balanced by=thc action of the bellows and the diaphragm 44.

In correct assembly both valves 26 and 29 *contact the spacer 3|, with the'valve 26 con- 'tactin'g theseat 24 'and the valve 29 contacting r the lower end of the tube 38. If conditions are not entirely correct the relationship may be varled to obtain them, by changing the tension of Lthespring52 by means of thenuts 53. In practice it is preferred that the nuts 53 be so disposed as to provide an initial tension on the spring ,52 in such manner that the initial balancebetween the pull of the spring 52 and that or the magnet produce a pressure on the nut .42 sufllcient'to reduce the tension in the bellows .,;36 and diaphragm 44 and establish contact beinto the interior of U tween the tube 38 and the ball 'valve 29 with a .few pounds pressure to spare. Any value of such pressure below 5 lbs. has been'found to be satislactory. In describing theoperation, however, it is assumed that the initial condition is such as to provide a contact between the tube 38 and the ball 29 without pressure. Any additional pressure added merely corresponds to an initial tension in the spring 52 and such added pressure will be preserved through the workingrange oi the regulator.

.It will be noted that theposition' of the ball l a positionsuch thatit engages the nut 42. .-The s valves and of the bellows varies very littl durmg operation. The ball valves are completely open when they move 3% of an inch and equilibrium conditions i are establishedwith displacementsjof a few thousandths of an inch. Hence, the device operates by balancing forces, and not by moving from one position 'to another, and therefore the spring reaction can be considered as remaining constant during'operation'.

'As above mentioned, with oil entering the chamber 2| at 120 lbs; pressure per square inch,

pressure transmitted through the ball valve 29 q In the position shown'in Fig. i the tension oi the spring 52 is entirely counterbalanced by pressure of the and diaphragm.

the total pressure on the ball 25 is 18 lbs. Of this pressure, 10 lbs. are balanced by the bellows Ifa pressure'of 8 lbs. is applied by the set screw 6| on the head 42 the downward pressure on the ball 26 becomes 18 lbs., and the ball is in equilibrium. Any additional pressure on the head 42 willcause the the magnet 55. and the lever 5| in an extreme position in which there is no pressure exerted by the set screw 6| mentioned later. When usedin'a brake system other than an initial pressure ball valve 26 to open and allow oil to pass through the bore 39into the chamber 21 and bellows 36.

If the additional pressure were 10 lbs., or a total of 18-lbs.,b all valve 26 will be unseated until a balancing pressur of lbs. is developed in the bellows 36. With a bellows having an active area of Aiinch this will be attained when the oil pressure therein is 40 lbs. per square inch, at which time the ball valve will again become seated and will stop the flow. In the same manner, if the pressure on the screw 6| i increased further in 10 lb. amounts, to 28 and to 38 lbs., the balancing oil pressur in the bellows H and at the port 32 will be 80 and 100 lbs. per square inch respectively. Therefore, it will be seen that with any pressure P applied by the screw 6| there will be a balancing pressure at the port 32 equal to 4(P-8) lbs. per square inch.

If the pressure of 28 lbs. exerted by the screw 6| which has caused a pressure of 80 lbs. per sq. in. to build up in the bellows and at the port 32, is lowered to 18 lbs., the pressure in the bellows causes the tube 38 to lift above the valve 29. Oil then discharges through the tube 38,

ports 48 and port 49 until a new balancing pres-' sure 4(188)=49 lbs. per sq. in. is established.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various changes may be made within the scope of the appended claims without departing from the spirit of the invention, and

- such changes are contemplated.

What is claimed is:

1. In a pressure regulating valve, a housing having a valve chamber with an inlet and an outlet, dual valves controlling said inlet and said outlet respectively, yielding means normally urging said inlet valve toward closed position, a movable member adapted to move in response to fluid pressure in said chamber for opening said outlet valve, and means for opposing movement of said last named member, said last named means comprising a spring storing suflicient energy to maintain said outlet valve closed through the expected range of fluid pressure and sumcient energy in addition thereto to open said inlet valve against the opposition of said yielding means, an electro-magnet for opposing the action of said spring through a range from zero opposition to a maximum overpowering said spring, and manually controllable means for energizing said magnet todegrees determined by the will of the operator.

2. In a pressure regulating valve, a housing having a valve chamber with an inlet and an outlet, dual valves controlling said inlet and said outlet respectively, yielding means normally urging said inlet valve to closed position, said '"s'tlet valve being normally closed, a movable member adapted to move in response to fluid pressure in said chamber for opening said outlet valve, and means for opposing movement of said last named member, said last named means comprising a balancing lever fulcrumed on said housing and adapted to press against said movable member, means exerting a constant pressure on said lever of a magnitude sumoient to maintain said outlet valve closed and sufficient to open said inlet valve, and manually operable means for exerting a force in opposition to said spring and which varies through a range from zero opposition to a magnitude completely nullifying action of the spring.

3. In a pressure regulating valve, a housing having a valve chamber with an inlet and an outlet, dual valves controlling said inlet and said outletrespectively, yielding means normally holding said inlet valve closed, a movable member adapted to move in response to fluid pressure in said chamber for opening said outlet valve,

and means for opposing movement of said last named member, said lastnamed means oomprising a balancing lever fulcrumed on said housing, a spring acting against one end of said lever for pivoting the same in one direction, means between said lever and said movable member for transmitting the pressure of said spring to said movable member for closing said outlet valve and opening said inlet valve, an electro-magnet for exerting a force on said lever in opposition to said spring, and a variable manual control for energizing'said magnet to varying degrees.

'4. In a pressure regulating valve assembly, a housing having a valve chamber with an inlet, a valve for closing said inlet, said valve having a spring yieldingly urging it closed and being so disposed thatwhen closed the, pressure of the fluid to be controlled tends to hold it closed, a valve in said chamber and connected to the first valve for movement the..-'-".with, a flexible sealing means closing said valvechamber, said sealing means having an outlet port adapted to seat against said second valve to prevent exhaust of fluid from said valve chamber, said movable memher being adapted to move in response to fluid pressure in said chamber. to separate the port from said second valve, and means for opposing action of said movable member, said last named means comprising a spring storing sufficient energy to hold said movable member with the outlet port closed and to unseat said first valve, an electro-magnet for opposing action of said spring, and manually controllable means for en ergizing said magnet.

5. In a pressure regulating valve assembly, a housing having a valve chamber with an inlet, a. valve for closing said inlet, said valve having a spring yieldingly urging it closed and being so disposed that when closed the pressure of the fluid to be controlled tends to hold it closed, a valve in said chamber and connected to the first valve for movement therewith, a flexible sealing means closing said valve chamber, said sealing means having an outlet port adapted to seat against said second valve to prevent exhaust of fluid from said valve chamber, said movable member being adapted to move in response to fluid pressure in said chamber to separate the port from said second valve, and means for opposing action of said movable member, said last named means comprising a balancing lever fulcrumed on said housing and adapted to press against said movable member, means exerting a constant pressure on said lever of a magnitude sufiicient to maintain said outlet valve closed and sufiicient to open said inlet valve, and-manually operable means for exerting a force in opposition to said spring and which varies'through a range from zero opposition to a magnitude completely nullifying action of the spring.

6. In a pressure regulating valve, a housing having a valve chamber with an inlet and an outlet. dual valves controlling said inlet and said outlet respectively, yielding means normally holding said inlet valve closed, a movable member adapted to move in response to fluid pressure in said chamber for opening said outlet valve, and means for an electro-magnet connected to the other end and acting in opposition to said spring.

7. In a pressure regulating valve, a fluid pressure chamber having a fluid inlet and a valve guarding said inlet, said valve being urged toward its'seat by a spring and also by pressure of fluid from a source of fluid pressure supply, a

' diaphragm forming a wall of, said chamber and having a tube therethrough constituting an outlet passage, a ball valve in said chamber closing.

said outlet passage, a spacer element between said inlet valve and saidoutlet valve, spring means in said outlet tube opposing seatingof said outlet ing 'a tube therethrough constituting an outlet passage, a ball valve in said chamber closing said outlet passage, a spacer element between said 7 inlet valve and said outlet valve, spring means in said outlet tube opposing seating of said outlet valve, said spring means opposing also the seating of said inlet valve through said outlet valve and said spacer, force regulating means for devalve, said spring means opposing also the seata 7 ing of said inlet valve through said outlet valve and said spacer, iorce regulating means for determining the pressure on said spring means comprising a balanced arm in contact with said spring means intermediate its ends having a spring exerting a pressure'o'n one end of said arm and having a manually controllable solenoid capable of exerting variable pressures on thejotherend;

thereof, said inletval'v'e opening when the force transmitted throughsaid spring means exceeds the combined pressure of the inlet valve spring and the fluid pressure thereagainst and closing 7 when the fluid pressure in said chamber balances I the unseating pressures oi said spring means,

said outlet valve opening upon decrease by said solenoid of pressure applied to said pressure means and remaining open during the period of unbalance therebetween.

8. In a pressure regulating valve, a fluid prestermining the pressure of said spring means comprising a balanced arm in contact with said spring means intermediate its ends having a spring exerting'a pressure on one end of said arm and having a manuallycontrollable solenoid capable oi exerting variable pressures on the other end thereof, said inlet valve opening when the force transmitted through said spring means exceeds the combined pressure of the inlet valve spring and the fluid pressure thereagainst and closing when the fluid pressure in said chamber balances the unseating pressures of said spring means, said outlet valve opening upon decrease by said .solenold oi pressure applied to said pressure means and remaining open during the period 01' V unbalance therebetween, said fluid chamber having a second outlet open to a second chamber having an expansible wall, said expansible wall being connected to mechanism for doing work.

EMIL H. PIRON. 

